Cleanup of methods in Actor and ActorContext trait. See #1377

* Added JavaActorContext, UntypedActor.getContext
* implicit val context in Actor needs to be implicit to support forward,
it would be nice if it wasn't implicit because now I can't override context
in UntypedActor
* Removed implicit def system in Actor
* Removed implicit def defaultTimeout in Actor
* Removed receiveTimeout, children, dispatcher, become, unbecome, watch,
unwatch in Actor
* Removed corresponding as above from UntypedActor
* Removed implicit from dispatcher in ActorSystem
* Removed implicit def timeout in TypedActor
* Changed receiveTimeout to use Duration (in api)
* Changed many tests and samples to match new api

akka-tutorials/akka-tutorial-first/src/main/scala/Pi.scala

@@ -52,11 +52,14 @@ object Pi extends App {
     var start: Long = _
 
     // create the workers
-    val workers = Vector.fill(nrOfWorkers)(system.actorOf[Worker])
+    val workers = Vector.fill(nrOfWorkers)(context.actorOf[Worker])
 
     // wrap them with a load-balancing router
+    // FIXME routers are intended to be used like this
+    implicit val timout = context.system.settings.ActorTimeout
+    implicit val dispatcher = context.dispatcher
     val props = RoutedProps(routerFactory = () ⇒ new RoundRobinRouter, connectionManager = new LocalConnectionManager(workers))
-    val router = new RoutedActorRef(system, props, self, "pi")
+    val router = new RoutedActorRef(context.system, props, self, "pi")
 
     // message handler
     def receive = {